Simplify the following expression: $\dfrac{28k^2}{36k}$ You can assume $k \neq 0$.
$ \dfrac{28k^2}{36k} = \dfrac{28}{36} \cdot \dfrac{k^2}{k} $ To simplify $\frac{28}{36}$ , find the greatest common factor (GCD) of $28$ and $36$ $28 = 2 \cdot 2 \cdot 7$ $36 = 2 \cdot 2 \cdot 3 \cdot 3$ $ \mbox{GCD}(28, 36) = 2 \cdot 2 = 4 $ $ \dfrac{28}{36} \cdot \dfrac{k^2}{k} = \dfrac{4 \cdot 7}{4 \cdot 9} \cdot \dfrac{k^2}{k} $ $\phantom{ \dfrac{28}{36} \cdot \dfrac{2}{1}} = \dfrac{7}{9} \cdot \dfrac{k^2}{k} $ $ \dfrac{k^2}{k} = \dfrac{k \cdot k}{k} = k $ $ \dfrac{7}{9} \cdot k = \dfrac{7k}{9} $